Organization and Significant Accounting Policies - Activity in Polaris Accrued Warranty Reserve (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Activity in Product Warranty Reserve [Roll Forward]
Balance at beginning of year	$ 136,200	$ 121,800	$ 123,800
Additions to reserve related to acquisitions	0	8,800	19,500
Additions charged to expense	123,700	122,900	105,000
Warranty claims paid, net	119,100	117,300	(126,500)
Balance at end of year	$ 140,800	$ 136,200	$ 121,800